1. Field of the Invention
The present invention generally relates to video processing, and more particularly to a film-mode video stream handling method and system.
2. Description of the Related Art
Unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Moving picture video is typically recorded or encoded at a predetermined frame rate. For example, cinema films are typically recorded at one predetermined rate (e.g., 24 frames per second). On the other hand, a video broadcast for an interlaced television (such as a national television system committee (NTSC) television or a phase alternating line (PAL) television) is encoded at another predetermined rate (e.g., 60 video fields per second). For the cinema film to be properly displayed on the interlaced television, a conversion of the cinema film is required. To convert the video of the cinema film encoded in the predetermined frame rate to be in compliance with the interlaced television standard, a technique of dropping or repeating frames within a frame sequence is a viable option. Such technique includes a 3:2 pull down and a 2:2 pull down. The 3:2 pull down is for generating a patterned sequence of the frames starting with a 3-video field frame followed by a 2-video field frame or vice versa. Similarly, the 2:2 pull down is to prepare another patterned sequence of consecutive 2-video-field frames. The frames processed by the 3:2 pull down or the 2:2 pull down are categorized as film-mode video streams.
A hybrid video stream may include one or more film-mode video streams and one or more non-film-mode video streams. The film-mode video streams may be properly displayed on a non-interlaced display device, after having pairs of the video fields carrying the same frame in the hybrid video stream identified to minimize potential ragged transition artifacts. Meanwhile, certain spatial or temporal interpolation is also needed to properly display the non-film-mode video frames on the non-interlaced display device with minimal artifacts. Because the film-mode video streams and the non-film-mode video streams are processed differently, detecting and handling film-mode video streams in a hybrid video stream ensures the proper display of such a hybrid video stream.
In addition, a video stream may include one or more bad edits. A “bad edit” generally refers to a break of a pattern in the video stream. For example, by erroneously switching out of a 3:2 film-mode operating mode, incorrect video fields may be processed, possibly introducing additional transition artifacts at the time of display.